html, body, #root{
  width: 100%;
  height: 100%;
}

html,
body,
title,
meta,
div,
ul,
ol,
header,
footer,
section,
aside,
article,
a,
p,
span,
em,
i,
input,
button,
blockquote,
address,
audio,
video,
nav,
canvas,
select,
small,
source,
dd,
dl,
dt,
table,
tbody,
hgroup,
embed,
frame,
img,
link,
label,
option,
td,
th,
tr,
tt,
style {
  margin: 0;
  padding: 0;
}

.hvc {
  position: absolute;
  left: 50%;
  top: 50%;
  transform: translate(-50%, -50%);
}

/*轴定义： 取决于flex-direction: column(主轴垂直方向，交叉轴水平方向) row(主轴水平方向，交叉轴垂直方向)*/

/*默认水平方向 排序*/

.flex {
  display: -webkit-box;
  display: -webkit-flex;
  display: -ms-flexbox;
  display: flex;
}

/*垂直方向 排序*/

.flex-v {
  -webkit-box-orient: vertical;
  -webkit-flex-direction: column;
  -ms-flex-direction: column;
  flex-direction: column;
}

.flex-1 {
  -webkit-box-flex: 1;
  -webkit-flex: 1;
  -ms-flex: 1;
  flex: 1;
}

.flex-2 {
  -webkit-box-flex: 2;
  -webkit-flex: 2;
  -ms-flex: 2;
  flex: 2;
}

.flex-wrap {
  flex-wrap: wrap;
}

/*交叉轴对齐方向 */

.flex-align-center {
  -webkit-box-align: center;
  -webkit-align-items: center;
  -ms-flex-align: center;
  align-items: center;
}

/*左对齐*/

.flex-align-top {
  -webkit-box-align: center;
  -webkit-align-items: flex-start;
  -ms-flex-align: center;
  align-items: flex-start;
}

/*右对齐*/

.flex-align-bottom {
  -webkit-box-align: center;
  -webkit-align-items: flex-end;
  -ms-flex-align: center;
  align-items: flex-end;
}

/*居中对齐*/

.flex-pack-center {
  -webkit-box-pack: center;
  -webkit-justify-content: center;
  -ms-flex-pack: center;
  justify-content: center;
}

.flex-pack-end {
  -webkit-box-pack: center;
  -webkit-justify-content: flex-end;
  -ms-flex-pack: center;
  justify-content: flex-end;
}

/*分散对齐*/

.flex-pack-justify {
  -webkit-box-pack: justify;
  -webkit-justify-content: space-between;
  -ms-flex-pack: justify;
  justify-content: space-between;
}

/*距离盒子两边间距相同*/

.flex-pack-around {
  -webkit-box-pack: justify;
  -webkit-justify-content: space-around;
  -ms-flex-pack: justify;
  justify-content: space-around;
}
